1. Field of the Invention
The invention relates to a gate driving apparatus, and more particularly, to a bootstrap gate driving apparatus.
2. Description of Related Art
Please refer to FIG. 1. FIG. 1 illustrates a circuit diagram of a conventional gate driving apparatus 100. The gate driving apparatus 100 includes an integrated circuit 110, a bootstrap diode DB, a boost capacitor CB, and transistors Q1, Q2. The gate driving apparatus 100 provides electrical signals through alternative switching actions of the transistors Q1, Q2 to drive the inductor L which serves as a load.
The transistors Q1 and Q2 are serial coupled between a power voltage VDC and a reference ground voltage GND sequentially, and the transistors Q1 and Q2 respectively receive a high-end driving signal HO and a low-end driving signal LO of the integrated circuit 110 to become conductive or disconnected. The boost capacitor CB is serial coupled between the base voltage VS and the bias voltage VB provided by the integrated circuit 110. As the gate driving apparatus 100 is undergoing an operation, the transistor Q2 first becomes conductive such that the integrated circuit 110 provides a power voltage VDD to charge the boost capacitor CB to the power voltage VDD through the bootstrap diode DB. Moreover, as the transistor Q1 is conductive and after the transistor Q2 is disconnected, the bias voltage VB may be pulled up to VDC+VDD by the boost capacitor CB, and the high-end driving signal HO produced according to the bias voltage VB is also pulled up to VDC+VDD accordingly.
Herein, the bootstrap diode DB must have an ability to withstand high reverse bias voltage, so that as the bias voltage VB is charged to high, no refluxed current back to the power voltage VDD is produced. Therefore, an additional plug-in bootstrap diode DB outside the integrated circuit 110 is often used to construct in conventional techniques, and such approach may result in increased cost of the circuit.
In addition, in the conventional techniques, a switching transistor and a control circuit may also be disposed in the integrated circuit 110. Through the control circuit, the conduction or the disconnection of the switching transistor is controlled, such that the boost capacitor CB may perform the pull-up actions, and possibilities that the refluxed current refluxes back to the power voltage VDD are prevented. However, such approach requires extra control circuit to complete, which requires a higher cost of the circuit.